1. Field of the Invention
The present invention relates to a thermal printer which can effectively perform the image recording on a recording medium.
The thermal printer according to the present invention can be adapted to a color printer which can output a color image from a color computer graphics or a color video player, a facsimile, a copying machine, a word processor or the like.
2. Related Background Art
In the past, in order to record on image by using such a recording apparatus, for example a facsimile, there was used a recording system wherein electric current corresponding to signals is supplied to exothermic elements (thermal head) and a desired image is formed on a heat-sensitive recording medium according to the heated elements, or a recording system wherein a black-and-white image is formed on a recording medium by thermally transferring ink from a black inked ribbon by means of such thermal head has been used.
On the other hand, color printers which can print a color image in the color computer graphics and color video players have recently been developed. For example, there has been proposed a recording apparatus using the afore-mentioned thermal head wherein soluble or sublimable colors such as yellow (Y), magenta (M), cyan (C) and black (Bk) painted on an inked sheet are transferred on the recording medium by means of the thermal head, thereby obtaining multi-color and multi-harmonization images.
However, if it is desired that a black-and-white image be obtained by the above-mentioned color printer, three colors (Y), (M), (C) must be transferred to the same area on the recording medium, or a composite circuit for composing three color (Y,M,C) signals to obtain a luminance signal must be provided so that the image is recorded by using a black inked sheet alone on the basis of such luminance signal.
Further, only when only a black-and-white image is to be recorded, an ink cassette including a black inked ribbon can be used; however, in this case, an operator must change the ink cassettes each time with respect to different kinds of images.
On the other hand, in case of a printing apparatus of a transmission system which can transmit and receive both the black-and-white image and the color image and which can continuously and repeatedly record or print the black-and-white images and the color images at random, both a color printer and a printer for the black-and-white images (black-and-white printer) must be used, thus making the whole system complicated and large-sized.
In addition, in the above system, there is a problem that, when the recording papers for the color image or the recording papers for the black-and-white image are used up during a continuous recording operation, the whole system must be stopped to replenish the vacant papers.